cry it out method

Hi Mama's!

My daughter will be 7 months next week and is only sleeping an hour to an hour and a half at night and then is up. If she is not being rocked and held she is screaming as soon as she is put down. She is also like this for naps too. On a good day she only gets one 30-45 min nap. She is overly tired and so am I.

She is breastfed and I've even considered giving that up thinking it might be an attachment thing as to why she just wants to be held or cuddle with me in my bed.

I am lost on what to do... considering cry it out as our last resort but I'm not sure how to go about it. How long do you let them cry? And when they wake back up in an hour or so do you leave them or get them and feed them?

thank you!